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US3794899A
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Servo motor driven encoder error evaluation system
Assignee: MOTION SYSTEMS COMPANY Inc
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Filing: 1972-06-19
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Granted: 1974-02-26
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Expires: 1992-06-19
Abstract
Abstract Disclosed is a system for evaluating errors in high precision encoders. A phase-lock servo system provides accurate and constant shaft speed control of an encoder under test and integration capability is provided to average either angle or time readings obtained during a plurality of revolutions of the encoder and thereby reduce the random errors originating in the testing apparatus. Also provided is a speed perturbation generator for checking the system''s operability.
Inventors
- 👤 D Breslow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:45
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/27; G05B19/29; Y; Y10; Y10S; Y10S388/00; Y10S388/907; Y10S388/911; Y10S388/912
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
203 words
A system for testing for errors in an angular encoder which converts an angular position into a representative digital signal and comprising: a. a reference input generator means for producing a reference signal; b. a phase-lock servo means responsive to the reference signal, said phase-lock servo means adapted to rotate an encoder under test at a known angular velocity and including a transdUcer means operatively associated with the encoder under test for producing an output signal; c. a first sensing means operatively associated with the encoder under test for detecting a first predetermined angular position thereof; d. a second sensing means operatively associated with the encoder under test for detecting a second predetermined angular position thereof; e. a clock means operatively associated with said first sensing means and said second sensing means for measuring the time elapsed as the encoder rotates from said first predetermined angular position to said second predetermined angular position; and f. means for taking a plurality of readings of the time elapsed as the encoder rotates from said first predetermined angular position to said second predetermined angular position during a plurality of revolutions of the encoder to average out errors in the system unrelated to errors in the encoder.
Claim 2
Independent Claim
203 words
A system for testing for errors in an angular encoder which converts an angular position into a representative digital signal and comprising: a. a reference input generator means for producing a reference signal; b. a phase-lock servo means responsive to the reference signal, said phase-lock servo means adapted to rotate an encoder under test at a known angular velocity and including a transdUcer means operatively associated with the encoder under test for producing an output signal; c. a first sensing means operatively associated with the encoder under test for detecting a first predetermined angular position thereof; d. a second sensing means operatively associated with the encoder under test for detecting a second predetermined angular position thereof; e. a clock means operatively associated with said first sensing means and said second sensing means for measuring the time elapsed as the encoder rotates from said first predetermined angular position to said second predetermined angular position; and f. means for taking a plurality of readings of the time elapsed as the encoder rotates from said first predetermined angular position to said second predetermined angular position during a plurality of revolutions of the encoder to average out errors in the system unrelated to errors in the encoder.
Claim 3
Dependent Claim
26 words
An encoder evaluation system according to claim 1 including a correlator means for correlating the reference input signal and the output signal of said transducer means.
Claim 4
Dependent Claim
28 words
An encoder error evaluation system according to claim 1 wherein said servo means comprises a perturbation generator means for introducing a predetermined perturbation in the reference input signal.
Claim 5
Dependent Claim
80 words
A system as set forth in claim 1 wherein said means for taking a plurality of readings includes means for storing a plurality of values with each of said plurality of values representing the elapsed time for the encoder to rotate from said first predetermined angular position to said second predetermined angular position during a particular revolution of the encoder, whereby errors in the system unrelated to errors in the encoder are averaged out by the plurality of stored values.
Claim 6
Dependent Claim
17 words
An encoder evaluation system according to claim 4 wherein said storing means comprises a digital register means.
Claim 7
Dependent Claim
38 words
An encoder error evaluation system according to claim 5 wherein said digital register means comprises a plurality of digital registers, each responsive to the time measured by said clock means during a different one of the angular motions.
Claim 8
Dependent Claim
40 words
An encoder error evaluation system according to claim 1 wherein said means for taking a plurality of readings includes a comparator means for detecting differences between the times measured during different rotations of the encoder and a predetermined theoretical time.
Claim 9
Dependent Claim
18 words
An encoder error evaluation system according to claim 1 wherein said clock means produces a digital timing signal.
Claim 10
Dependent Claim
17 words
An encoder error evaluation system according to claim 8 wherein said clock means comprises a crystal oscillator.
Claim 11
Dependent Claim
19 words
An encoder error evaluation system according to claim 1 wherein said reference input generator means comprises a crystal oscillator.
Claim 12
Dependent Claim
144 words
An encoder error evaluation system according to claim 1 wherein: a. said first sensor means comprises a plurality of first sensors, each of said first sensors adapted to determine a distinct first angular position of the encoder under test; b. said second sensor means comprises a plurality of second sensors each of said second sensors adapted to determine a distinct second angular position of the encoder under test, and each of said second sensors being associated with a different one of said first sensors so as to establish therewith a discrete angular test segment; and c. said clock means comprises a plurality of separate and independent clocks, each of said clocks being operatively associated with a different one of said first sensors and adapted to measure the time elapsed as the encoder under test rotates through a different one of the discrete test segments.
Claim 13
Dependent Claim
61 words
An encoder error evaluation system according to claim 11 including a comparator means comprising a plurality of separate and independent comparator sections, each one associated with a different one of said plurality of clocks, each of said comparator sections adapted to detect differences betweeN the time measured by a different one of said plurality of clocks and a predetermined theoretical time.
Claim 14
Dependent Claim
182 words
An encoder error evaluation system comprising: a. a reference input generator means for producing a reference signal; b. a phase-lock servo means responsive to the reference signal, said phase-lock servo means adapted to rotate an encoder under test at a known angular velocity and including a transducer means operatively associated with the encoder under test for producing an output signal; c. an angular sensing means operatively associated with the encoder under test for detecting a predetermined angular position thereof; d. a timing means operatively associated with said angular sensing means for measuring a predetermined time interval beginning when said angular sensing means detects the predetermined angular position; e. an angular position recorder operatively associated with said timing means for determining the angular position of the encoder under test as indicated by the output signal at the expiration of the predetermined time interval; and f. means for taking a plurality of readings of the angular position determined by said angular position recorder during a plurality of revolutions of the encoder to average out errors in the system unrelated to errors in the encoder.
Claim 15
Dependent Claim
182 words
An encoder error evaluation system comprising: a. a reference input generator means for producing a reference signal; b. a phase-lock servo means responsive to the reference signal, said phase-lock servo means adapted to rotate an encoder under test at a known angular velocity and including a transducer means operatively associated with the encoder under test for producing an output signal; c. an angular sensing means operatively associated with the encoder under test for detecting a predetermined angular position thereof; d. a timing means operatively associated with said angular sensing means for measuring a predetermined time interval beginning when said angular sensing means detects the predetermined angular position; e. an angular position recorder operatively associated with said timing means for determining the angular position of the encoder under test as indicated by the output signal at the expiration of the predetermined time interval; and f. means for taking a plurality of readings of the angular position determined by said angular position recorder during a plurality of revolutions of the encoder to average out errors in the system unrelated to errors in the encoder.
Claim 16
Dependent Claim
27 words
An encoder error evaluation system according to claim 13 including a correlator means for correlating the reference input signal and the output signal of said transducer means.
Claim 17
Dependent Claim
28 words
An encoder error evaluation system according to claim 13 wherein said servo means comprises a perturbation generator means for introducing a predetermined perturbation in the reference input signal.
Claim 18
Dependent Claim
69 words
A system as set forth in claim 13 wherein said means for taking a plurality of readings includes means for storing a plurality of values with each of said plurality of values representing an angular position determined by said angular position recorder during a particular revolution of the encoder, whereby errors in the system unrelated to errors in the encoder are averaged out by the plurality of stored values.
Claim 19
Dependent Claim
18 words
An encoder error evaluation system according to claim 13 wherein said storing means comprises a digital register means.
Claim 20
Dependent Claim
45 words
An encoder error evaluation system according to claim 17 wherein said digital register means comprises a plurality of digital registors each responsive to the indicated positions determined by said angular position recorder during a different one of the sequential rotations of the encoder under test.
Claim 21
Dependent Claim
42 words
An encoder error evaluation system according to claim 13 wherein said means for taking a plurality of readings includes a comparator means for detecting differences between the angular positions determined during different revolutions of the encoder and a predetermined theoretical angular position.
Claim 22
Dependent Claim
18 words
An encoder error evaluation system according to claim 13 wherein said timer means produces a digital timing signal.
Claim 23
Dependent Claim
17 words
An encoder error evaluation system according to claim 20 wherein said timer means comprises a crystal oscillator.
Claim 24
Dependent Claim
19 words
An encoder error evaluation system according to claim 21 wherein said reference input generator means comprises a crystal oscillator.
References Cited (Backward Citations)
US3465223A
Cited
US3654479A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |